Lid with tube reinforced skirt

ABSTRACT

A lid for a container is disclosed. The lid has a paperboard tube that surrounds a plastic resin skirt. The skirt is attached to the perimeter of a central panel, which may also be formed of paperboard. The tube may have a projecting portion that is deformed toward the central panel. The tube provides an outwardly facing surface for the display of high quality graphics. A method of making the lid is also disclosed. The method includes placing the tube within a mold and injecting plastic resin into the mold to form the skirt. The central panel may also be placed in the mold prior to molding. Engagement of the mold with the tube may be used to deform the projecting portion of the tube.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 60/730,325, filed Oct. 26, 2006.

FIELD OF THE INVENTION

This invention relates to lids for containers and especially to composite type lids formed from a combination of paper and plastic materials.

BACKGROUND OF THE INVENTION

Containers used for packaging foodstuffs, as well as other products for retail sale, must perform several functions. The container must hold the product, must allow the product to be transported effectively from the manufacturer to the point of sale, and from the point of sale to the consumer, must often serve to dispense and store the product after acquisition by the consumer, and no less importantly, must identify the product and its source and serve as an advertising medium and to promote further sales.

It is desirable that the containers be inexpensive to manufacture, yet durable so as to continue to perform their various functions effectively despite abuse and harsh environments.

The container lid plays an important role in the proper functioning of the container. It is desirable that the lid effectively close the container, and when the container is used to store and dispense the product, it is also desirable that the lid be removable and reclosable many times over the life of the container. Ice cream containers provide a good example of a container used to store and dispense the product held in the container. Ice cream containers are also subject to conditions of freezing, thawing, moisture and repeated opening and closing of the lid, all of which tend to cause deterioration and rapid failure of the container unless it is properly designed and manufactured.

It has been found advantageous to make the lids for such containers as a composite combination of both paper and plastic materials. The designs currently in use comprise an injection molded plastic skirt surrounding a paperboard center. The plastic skirt fits over the end of the container engaging the end and/or sides, thereby sealing the container and providing a means for retaining the lid in the closed position. Plastic is used for the skirt because it is inexpensive, easy to mold, resilient, impervious to freezing, thawing and moisture and relatively rigid. The skirt is the portion of the lid which sees the most abuse during the life of the container, and the above noted qualities of plastic allow the lid to maintain its shape and hold together to continue to effectively close the container despite the adverse environment and repeated handling.

It is not desirable, however, to make the entire lid from plastic. Plastic does not provide a surface capable of receiving the high-quality printed graphics needed for the container to fulfill its function as identifier of the product and its source and as an advertising medium for the product. Paper is the preferred medium for displaying high-quality graphics regarded as necessary to compete in the advertising environment of retail sales. Thus, the paperboard center provides the means for presenting complex, colorful and detailed graphics, such as illustrations of product, company trademarks and trade dress designs, while the plastic skirt provides a durable material impervious to abuse and environmental conditions.

A problem with the composite lid design described above is that the graphics are confined to the paperboard center portion of the lid and do not extend continuously over the plastic skirt. The absence of graphics over portion of the container is unacceptable to many product manufacturers who want a container which can receive printed media over the entire outer surface without interruption. Such continuity is important for the proper presentation of trademarks and trade dress, which are vital to customer recognition of a particular product from among the many competing products displayed side-by-side in a typical retail sales environment. There is clearly a need for a composite lid design combining the robustness and durability of the plastic skirt with the ability to receive high-quality graphics continuously over the entire surface of the lid without interruption.

SUMMARY OF THE INVENTION

The invention concerns a lid for a container. The lid comprises a panel and a skirt surrounding the panel. The skirt extends transversely to the plane of the panel and is formed from a plastic resin. The skirt is attached to the panel. A tube surrounds the skirt and is attached thereto. The tube is formed of paperboard. Preferably, the panel is also formed of paperboard but could also be formed of a polymer and may be opaque, translucent or transparent.

Preferably, the tube comprises a spiral wound paperboard tube. Other types of tubes are also feasible and include a tube formed by joining ends of a paperboard substrate using a butt joint, an overlap joint or a scarf or skived joint. The tube may be a simple cylindrical tube or comprise a first portion attached to the skirt and a second portion that projects beyond the skirt and is deformed inwardly toward the panel.

The invention also concerns a method of making a lid for a container having a panel attached to a skirt of plastic resin surrounded by a paperboard tube. The method comprises:

(a) providing a mold;

(b) opening the mold;

(c) positioning the tube within the mold;

(d) closing the mold; and

(e) injecting a plastic resin into the mold to form the skirt surrounding the panel, the skirt adhering to an inwardly facing surface of the tube, the tube and the skirt being oriented transverse to the panel.

The method may also include positioning a paperboard substrate within the mold. The paperboard substrate comprises the panel, and skirt adheres to the panel.

The method may further include engaging a portion of the tube with the mold upon closing of the mold to deform a portion of the tube inwardly toward the panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a lid and container embodiment according to the invention;

FIG. 2 is a sectional view of the lid shown in FIG. 1;

FIG. 3 is a partial sectional view taken on an enlarged scale from FIG. 2;

FIGS. 4-7 are perspective views of paperboard tubes used with the invention; and

FIG. 8 is a detailed partial top view taken at line 8-8 of FIG. 7.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows an embodiment of a lid 10 according to the invention. Although a round lid is illustrated, it is by way of example only, it being understood that the lid shape is not limited to the round shape shown. Lid 10 comprises a central panel 12 surrounded by a skirt 14. Skirt 14 extends transversely to the plane of the panel 12 and is adapted to receive the rim 13 of a container 15 for closing and opening the container. Container 15 comprises a sidewall 17 and a bottom 19 positioned opposite to the rim 13.

FIG. 2 shows a cross sectional view of lid 10. Central panel 12 is preferably formed of paperboard to provide a surface for imprinting of high quality indicia and graphics. Alternately, the panel 12 could be formed from a plastic resin, which could be the same or different from the resin forming the skirt. The panel could also be transparent, translucent or opaque as desired for the particular packaging.

Skirt 14 is attached to the perimeter 16 of panel 12 and is preferably formed from plastic resin. The skirt may have various features molded in, such as the inwardly protruding lip 18 which engages a rolled edge around the rim of a container (not shown) to help secure the lid to the container while still allowing it to be removable. Other features, such as ribs which stiffen the lid and/or facilitate the distribution of resin during the molding process may also be integrally formed with the skirt.

As best shown in detail in FIG. 3, the skirt 14 is surrounded by a paperboard tube 20, the skirt being attached to the inwardly facing surface 22 of the tube. Tube 20, being paperboard, provides an outwardly facing surface 24 that readily accepts high quality printed graphics which cannot be reproduced on the plastic resin skirt 14. Tube 20 may extend only over the skirt 14, or as illustrated, the tube may comprise a first portion 26 attached to the skirt 12, and a second portion 28 which projects beyond the skirt and is deformed inwardly toward the central panel 12. Curved tube portion 28 provides an outwardly facing imprinting surface 30 for continuity over the top of lid 10 of any indicia or graphics imprinted on the side surface 24 of tube 20. When deformed portion 28 is present, it may be formed in a tool before the tube is placed in a mold for injection molding of the skirt, or it may be formed upon closing of the mold after the tube is inserted but before plastic resin is injected to form skirt 14.

FIGS. 4-7 illustrate various examples of tubes 20 useable to form the lid 10 according to the invention. FIG. 4 shows a tube 20 a comprising a spiral wound paperboard tube 32. The spiral wound tube is particularly advantageous because it has great hoop strength and reinforces the skirt over its entire circumference substantially uniformly. FIG. 5 shows a tube 20 b comprising an elongated paperboard substrate 34 having opposite ends positioned to form a butt joint 36. FIG. 6 shows a tube 20 c formed from an elongated paperboard substrate 38 having ends attached in overlapping relation to one another to form a lap joint 40. FIG. 7 illustrates yet another tube 20 d comprising an elongated paperboard substrate 42 wherein the ends of the strip are in overlapping relation but are thinned to form a scarf or skived joint 44, illustrated in detail in FIG. 8.

Lids 10 according to the invention may be produced in a cavity and core mold. A process for their production includes positioning a paperboard tube, such as any of tubes 20 a-20 d within the mold, and positioning a paperboard or plastic central panel within the mold as well. The mold is then closed and plastic resin is injected. The resin adheres to the paperboard tube and the plastic or paperboard central panel and provides structural integrity to the lid thus formed. Adherence of the plastic to the paperboard is ensured by choosing a plastic, such as polystyrene, that naturally adheres to paper upon curing from a molten state, or by coating the paperboard components with a resin or other coating that is compatible with a molten plastic, such as polypropylene, upon injection and curing within the mold. As noted above, the mold may also be used as a tool to shape the paperboard tube, for example, by engaging a portion of the mold with a portion of the tube upon closing of the mold to deform the tube portion into a curved shape, such as the curved portion 28 shown in FIGS. 1-3.

Plastic resins that are feasible for lids as described herein include polypropylene, polyethylene, polystyrene to cite several examples.

Lids according to the invention combine dissimilar materials in the form of plastic resin and paperboard to each material's inherent advantage to provide a composite lid that is economical to produce, robust, impervious to harsh environments, and has an outer surface substantially over the entire lid that is capable of receiving a print media for the display of high-quality graphics. 

1. A lid for a container, said lid comprising: a panel; a skirt surrounding said panel and extending transversely to the plane thereof, said skirt being formed from a plastic resin and attached to said panel; and a tube surrounding said skirt and attached thereto, said tube being formed of paperboard.
 2. A lid according to claim 1, wherein said panel is formed of paperboard.
 3. A lid according to claim 1, wherein said panel is formed of plastic resin.
 4. A lid according to claim 3, wherein said panel is transparent.
 5. A lid according to claim 1, wherein said tube comprises a spiral wound tube.
 6. A lid according to claim 1, wherein said tube is formed by joining ends of a paperboard substrate using a butt joint.
 7. A lid according to claim 1, wherein said tube is formed by joining ends of a paperboard substrate using an overlap joint.
 8. A lid according to claim 1, wherein said tube is formed by joining ends of a paperboard substrate using a scarf joint.
 9. A lid according to claim 1, wherein said tube comprises a first portion attached to said skirt and a second portion that projects beyond said skirt and is curved inwardly toward said panel.
 10. A lid for a container, said lid comprising: a paperboard tube having an inwardly facing surface; a plastic resin skirt attached to said inwardly facing surface and extending around said tube; and a panel having an outer perimeter attached to said skirt.
 11. A lid according to claim 10, wherein said panel is formed of paperboard.
 12. A lid according to claim 10, wherein said tube comprises a first portion attached to said skirt and a second portion that projects beyond said skirt and is deformed inwardly toward said panel.
 13. A lid according to claim 10, wherein said tube has a round cross-sectional shape.
 14. In combination, a container and a lid, said container comprising: a bottom; a sidewall surrounding said bottom; an opening defined by a rim positioned on said sidewall opposite to said bottom, wherein; said lid comprises: a paperboard tube having an inwardly facing surface; a plastic resin skirt attached to said inwardly facing surface and extending around said tube, said skirt being adapted to receive said rim; and a panel having an outer perimeter attached to said skirt.
 15. A lid according to claim 14, wherein said panel is formed of paperboard.
 16. A lid according to claim 14, wherein said tube comprises a first portion attached to said skirt and a second portion that projects beyond said skirt and is deformed inwardly toward said panel.
 17. A method of making a lid for a container, said lid having a panel attached to a skirt of plastic resin, said skirt being surrounded by a paperboard tube, said method comprising: providing a mold; opening said mold; positioning said tube within said mold; closing said mold; and injecting a plastic resin into said mold to form said skirt surrounding said panel, said skirt adhering to an inwardly facing surface of said tube, said tube and said skirt being oriented transverse to said panel.
 18. A method according to claim 17, further comprising positioning a paperboard substrate within said mold, said paperboard substrate comprising said panel, said skirt adhering to said panel.
 19. A method according to claim 17, further comprising engaging a portion of said tube with said mold upon said closing thereof to deform a portion of said tube inwardly toward said panel. 